Solenoid regulated pump assembly

ABSTRACT

A pump assembly for flowing high-pressure liquid to components of an internal combustion engine includes a high-pressure pump, a hydraulic inlet throttle valve for the pump and a fast acting on—off solenoid control valve for flowing liquid at output pressure to the inlet throttle valve.

[0001] This application claims the benefit of U.S. ProvisionalApplication No. 60/427,094 filed Nov. 18, 2002.

FIELD OF INVENTION

[0002] The invention relates to pump assemblies and methods for pumpinghigh-pressure liquid, typically engine oil or fuel, for actuating fuelinjectors, inlet and exhaust valves and other devices in internalcombustion engines.

DESCRIPTION OF THE PRIOR ART

[0003] Diesel engines with hydraulic electronic unit injectors andhigh-pressure pumps for supplying high-pressure liquid for actuating theinjectors are well known. U.S. Pat. No. 6,460,510 discloses a pumpassembly for supplying high-pressure liquid to fuel injectors where theassembly includes a high-pressure pump and an inlet throttle valve forcontrolling the volume of oil supplied to the pump. The inlet throttlevalve is moved between open and closed positions. A spring biases theinlet throttle valve spool toward a full open position. Hydraulic fluidis supplied to the inlet throttle valve through a modulated relief valveto bias the spool toward a closed position. The relief valve iscontrolled by an analog voltage signal from the engine control module(ECM) proportional to the difference between the output pressure of thehigh-pressure pump and the desired output pressure of the high-pressurepump.

[0004] The conventional pump assembly works well and efficientlysupplies high-pressure liquid to injectors. Nonetheless, this assemblyflows some high-pressure liquid to sump with resultant energy loss andheat buildup. The assembly can be difficult to stabilize throughout theentire operating range of an engine.

[0005] Accordingly, there is a need for an improved pump assembly withimproved efficiency and stability.

SUMMARY OF THE INVENTION

[0006] The invention is an improved solenoid regulated pump assembly andmethod for flowing high-pressure liquid to fuel injectors, inlet andexhaust valves and other hydraulically-driven devices with improvedefficiency and stability.

[0007] The assembly includes a hydraulically actuated inlet throttlevalve and a hydraulic circuit for flowing high-pressure outlet liquid tothe inlet throttle valve and venting liquid from the inlet throttlevalve to sump using fast acting solenoid control valves responsive todigital (on—off) signals from the ECM. The signals indicate whether theoutput pressure of the high-pressure pump is greater or less than thedesired output pressure of the pump. Actuation of the fast actingsolenoid valves connects the inlet throttle valve to the output passageand supplies high-pressure liquid to the inlet throttle valve ordisconnects the inlet throttle valve from the output passage and ventsthe inlet throttle valve to sump to position the inlet throttle valvespool to a desired steady state position in which the flow from the pumpmaintains the desired output pressure without flow of high-pressureliquid to sump.

[0008] The solenoid control valve operates very rapidly to shift valvemembers between fully opened and fully closed positions withoutmodulating the flow through the valve. The valving members arepreferably small to reduce inertial forces and permit fast movementbetween the full open and full closed position so that the assemblyrapidly moves the inlet throttle spool to the desired position.

[0009] The improved pump assembly improves the fuel economy of theengine and decreases the need to dissipate heat by reducing the volumeof high-pressure oil flowed through the system and to sump. Duringsteady state operation of the engine, no high-pressure liquid is floweddirectly to sump through the system. The rapid response time for theassembly reduces the volume of high-pressure liquid used. The assemblyhas a fast response time and is stable.

[0010] Other objects and features of the invention will become apparentas the description proceeds, especially when taken in conjunction withthe accompanying drawings illustrating the invention, of which there aresix sheets and six embodiments.

DESCRIPTION OF THE DRAWINGS

[0011] FIGS. 1-3 illustrate circuit diagrams for three embodiments ofthe invention; and

[0012] FIGS. 4-6 illustrate three additional embodiments.

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0013] Six pump assemblies are disclosed. Each assembly includes ahigh-pressure pump and a hydraulically actuated spool-type inletthrottle valve, of the types disclosed in U.S. Pat. No. 6,460,510.

[0014] The inlet throttle valve includes a spring which biases the valvespool toward a full open position for flowing a high volume of oil tothe high-pressure pump. A pressure chamber at one end of the spool issupplied with pressurized oil for biasing the valve spool against thespring toward a minimum flow or closed position restricting the volumeof oil flowed to the high-pressure pump.

[0015] In each pump assembly, hydraulic fluid is flowed to and ventedaway from the inlet throttle valve by fast acting solenoid actuatedcontrol valves in response to signals from the electronic control module(ECM). Each system is part of an internal combustion engine withcomponents actuated by high-pressure fluid, typically a diesel enginewith hydraulic electronic unit fuel injectors. The pump assemblies mayactuate other components including inlet and exhaust valves.

[0016]FIG. 1 illustrates pump assembly 10 for an internal combustionengine having an ECM, a sump 12 for collecting engine oil and a lowpressure or lube pump 14 for flowing oil from the sump to thelubrication system for the engine through low pressure line 16. Theengine includes a number of hydraulically actuated fuel injectors 18 anda high-pressure output line 20 extending from assembly 10 to theinjectors.

[0017] Assembly 10 includes a high-pressure pump 22 driven by theinternal combustion engine and inlet throttle valve 24. Low pressureinlet line 26 extends from line 16 to an inlet port of valve 24. Inletpassage 28 extends from an outlet port of the inlet throttle valve tothe inlet port of pump 22.

[0018] High-pressure outlet line 20 is connected to the high-pressureoutlet port of pump 22. Pressure sensor 30 is connected to line 20 tosend a pressure signal to the ECM proportional to the pressure in line20.

[0019] Inlet throttle valve 24 includes a valving spool movable betweenopen and closed positions to throttle inlet flow of oil to pump 22.Spring 32 biases the spool toward the full open position. The spoolcomprises a piston on the end of the spool away from spring 32 whichfaces a pressure chamber in the valve communicating with pressure line34. The pressure in the chamber biases the spool toward the closedposition. The position of the spool in the valve, and the flow area ofthe inlet throttle valve, are determined by a pressure balance betweenthe spring force and the hydraulic force acting on the spool. Increasedpressure in the chamber moves the spool toward the closed position toreduce flow to pump 22. Correspondingly, decreased pressure in thechamber allows spring 32 to move the spool toward the open position toincrease flow to pump 22.

[0020] High-pressure oil from line 20 is flowed to the inlet throttlevalve 24 through fast acting solenoid controlled valve 36. Oil is flowedfrom valve 24 to sump 12 through fast acting solenoid controlled valve38. High-pressure branch line 40 extends from line 20 to the inlet portof valve 36. Line 42 extends from the outlet port of valve 36 to line34. Line 34 extends from the inlet throttle valve 24 to the inlet portof valve 38. Line 44 extends from the outlet port of valve 38 to sump12.

[0021] Solenoid controlled valves 36 and 38 each include a valvingmember, which may be a spool or a poppet, and a spring 46 biasing thevalving member toward a closed position, preventing flow of oil throughthe valve. Each valve also includes a solenoid 48 connected to the ECM.When actuated, each solenoid moves the valving member to an openposition. Valve 36 flows high-pressure oil from line 20 to the inletthrottle valve 24 to bias the spool toward the closed or minimum flowposition. Valve 38 drains oil from inlet throttle valve 24 to allowspring 32 to bias the spool toward the open position. The valves 36 and38 are fast acting, permitting very rapid control of valve 24 inresponse to signals from the ECM.

[0022] During operation of the engine, pressure sensor 30 and otherengine sensors provide information to the ECM which, in turn, generatesoutput signals to solenoids 48 of valves 36 and 38. When the desiredpressure in line 20 is greater than the sensed pressure in line 20, theECM deactivates solenoid 48 in valve 36 so that spring 46 closes thevalve. At the same time, the ECM actuates solenoid 48 of valve 38 toopen the valve and vent the inlet throttle valve to sump 12. Hydraulicpressure acting on the inlet throttle valve spool is reduced to allowspring 32 to shift the inlet throttle valve spool toward the full openposition to increase the flow of low pressure oil to pump 22 and thevolume of oil pumped into line 20 thereby increasing the pressure inline 20.

[0023] When the sensed pressure in line 20 is greater than the desiredpressure in line 20, the ECM actuates solenoid 48 of valve 36 to openthe valve and deactuates the solenoid 48 of valve 38 to close the valve.High-pressure fluid is flowed to the inlet throttle valve to bias thespool toward the closed position to reduce the volume of high-pressureoil flowed to pump 22 and output line 20 and reduce the pressure in theline. By appropriate selective actuation and deactuation of thesolenoids of valves 36 and 38, the inlet throttle spool is positioned asrequired to maintain the desired pressure in line 20.

[0024] An advantage of pump assembly 10 is that the inlet throttle spoolremains in a fixed position when both solenoids of valves 36 and 38 arenot actuated to facilitate steady-state operation of the engine. Duringsteady state operation valve 36 and 38 are closed to prevent flow ofhigh-pressure liquid from line 20 to the sump. Reduction of the volumeof high-pressure liquid flowed to the sump increases engine efficiencyand reduces heat formation and the need to dissipate released heat.

[0025] In the event of an over pressure in line 20, both valves 36 and38 may be opened to flow oil directly to sump 12 and rapidly decreasethe output pressure. Each open valve 36, 38 forms a restriction in theflow of high-pressure liquid from line 20 to sump. These restrictionsassure that line 34 and the inlet throttle valve is maintained at asufficiently high-pressure to shift the inlet throttle spool rapidlytoward the closed position during the period both valves 36 and 38 areopen to flow oil directly to sump so that flow to pump 22 and line 20 isreduced.

[0026] In pump assembly 10, fast acting solenoid valves 36 and 38 arenormally closed. Assembly 10 may be modified by providing normally opensolenoid control valves in place of disclosed valves 36 and 38. In sucha modified assembly, both valves are closed when energized. Thisarrangement has the advantage that the inlet throttle spool is alwaysshifted to a full open position when the system is shut down, and valve38 is opened to permit spring 32 to shift the inlet throttle valve spoolto the open position and flow oil to sump. The inlet throttle valve willbe wide open before start up, a requirement for hydraulic electronicunit injector diesel engines.

[0027]FIG. 2 illustrates a second embodiment of the invention andincludes elements corresponding to elements of the first embodiment.These elements are identified by the same reference numbers used indescribing the first embodiment and function as previously described.

[0028] High-pressure oil from line 20 is flowed to and from the inletthrottle valve 24 through dual solenoid controlled valve 136.High-pressure branch line 138 extends from line 20 to an inlet port ofvalve 136. Line 134 extends from the work port of valve 136 to the inletport of valve 24. Line 140 extends from an outlet port of valve 136 tosump 12.

[0029] Valve 136 includes a valving member or spool having a nullposition and end positions connecting line 138 to line 134 or connectingline 134 to line 140. Springs 142 and 144 bias the spool to the nullposition, preventing flow of oil through the valve. The valve alsoincludes solenoids 146 and 148 actuated by the ECM. When solenoid 146 isactuated, the spool is shifted to connect line 138 to line 134. Whensolenoid 148 is actuated the spool is shifted to connect line 134 toline 140.

[0030] When line 138 is connected to line 134, high-pressure oil fromline 20 flows to the inlet throttle valve 24. When line 134 is connectedto line 140, oil from valve 24 flows to the sump 12. The solenoids 146and 148 are fast acting, permitting rapid movement of the spool in valve24 in response to signals from the ECM.

[0031] During operation of the internal combustion engine, the fastacting dual valve 136 controls the position of the spool in inletthrottle valve 24 to throttle the flow of inlet oil through passage 28to pump 22. Inlet oil supplied to pump 22 is pumped to increase thepressure of the oil in line 20 supplied to injectors 18. If desired, anaccumulator may be provided in passage 20.

[0032] During operation of the engine, pressure sensor 30 and othersensors provide information to the ECM which, in turn, generates outputsignals to solenoids 146 and 148 on dual valve 136. When the sensedpressure in line 20 is greater than the desired pressure in line 20, theECM actuates solenoid 146 and deactuates solenoid 148 so that the spoolon valve 136 shifts to connect line 138 with line 134. This allowshigh-pressure oil from line 20 to flow to inlet throttle valve 24, movethe spool in the inlet throttle valve toward the closed position,decreasing the flow to pump 22 and decreasing the pressure in line 20.

[0033] Correspondingly, when the sensed pressure in line 20 is lowerthan the desired pressure in line 20, the ECM actuates solenoid 148 anddeactuates solenoid 146 so that the spool on valve 136 is shifted toconnect line 134 with line 140. This allows pressurized fluid in valve24 to flow to sump 12, decreasing the pressure in the chamber in inletthrottle valve 24 and allowing the spool to move toward the openposition. This increases the volume of high-pressure oil flowed intoline 28 and increases the output of pump 22 and the pressure in line 20.By appropriate selective actuation of the solenoids on valve 136 theinlet throttle spool is positioned as required to maintain desiredoutput pressure.

[0034]FIG. 3 illustrates a third embodiment of the invention andincludes elements corresponding to the elements in the first and secondembodiments. These elements are identified by the same reference numbersused in discussing the first embodiment.

[0035] Pump assembly 210 is part of an internal combustion engine havingan ECM, and includes a sump 12, low pressure pump 14, inlet throttlevalve 24, high-pressure pump 22, injectors 18 and as previouslydescribed.

[0036] High-pressure oil from line 20 is flowed to the inlet throttlevalve 24 through solenoid controlled valve 220. High-pressure branchline 222 extends from line 20 to an inlet port of valve 220. Line 224extends from the outlet port of valve 220 to an inlet port of valve 24.A branch of line 224 extends from line 224 through bleed orifice 226 tosump 12.

[0037] Solenoid controlled valve 220 has a valving member or spool and aspring 228 biasing the member toward a closed position, preventing flowof oil through the valve. The valve also includes a fast acting solenoid230 connected to the ECM. When actuated, the solenoid moves the spool toan open position. Valve 220 flows high-pressure oil from line 20 to theinlet throttle valve 24 to bias the spool toward the closed or minimumflow position. Oil in line 224 flows to the sump through bleed orificeor restriction 226. Valve 220 is fast acting, permitting very rapidopening and closing of valve 24 in response to signals from the ECM.

[0038] During operation of the engine, pressure sensor 30 and othersensors provide information to the ECM which, in turn, generates outputsignals to solenoid 230 on valve 220. When the sensed pressure in line20 is greater than the desired pressure in line 20, the ECM energizessolenoid 230 so that the valving member on valve 220 is shifted to anopen position. The valve flows high-pressure oil from line 20 to inletthrottle valve 24, moving the spool on the inlet throttle valve towardthe closed position, decreasing the flow to pump 22 and decreasing thepressure in line 20. The pressure drop across restriction 226establishes a pressure in line 224 to shift the inlet throttle spoolagainst spring 32.

[0039] When the sensed pressure in line 20 is less than the desiredpressure in line 20 the ECM deenergizes solenoid 230 so that the spoolon valve 220 is closed. This cuts off the flow of high-pressure oil fromline 20 to inlet throttle valve 24, reduces the pressure acting on thespool and moves the spool toward the open position, increasing the flowto pump 22 and increasing the pressure in line 20.

[0040] Bleed orifice 226 allows for a constant flow of fluid in line 224to the sump 12. When valve 220 is closed, excess pressurized fluid inline 224 returns to sump 12 facilitating opening of valve 24.

[0041] In pump assemblies 10, 110 and 210 the valves have fast actingsolenoids which shift the valving members rapidly between open andclosed positions in response to signals received from the ECM. The ECMsignals sent to the solenoids of these valves are digital signals, thatis, a signal is either “on” or “off.” An ECM “on” or “off” signalindicates whether the measured output pressure in line 20 is greaterthan or less than the desired output pressure. The solenoids of thevalves controlling flow to and from the inlet throttle valves areactuated or deactuated during the interval of ECM “on” and “off”signals.

[0042] In the embodiments of FIGS. 1 and 2, digital solenoid controlvalves permit steady state operation of the engine with the solenoidcontrolled valves closed to prevent flow of liquid to or from the inletthrottle valve. In this position, the inlet throttle valve cannot moveand the closed valves prevent flow of high-pressure fluid to the sumpwith resultant energy loss and generation of heat.

[0043]FIGS. 4, 5 and 6 illustrate pump assemblies 10′, 110′ and 210′which are identical to previously described assemblies 10, 110 and 210with the exception of orifices provided in the flow paths betweenpressure output line 20 and inlet throttle valve 24. The orificeprovides a pressure drop between the outlet pressure line and the inletthrottle valve to slow movement of the inlet throttle valve spool towardthe closed position when a valve opens quickly and liquid at outputpressure is flowed to the inlet throttle valve.

[0044] In FIG. 4, restriction 60 is provided in line 34 between line 42and inlet throttle valve 24. When valve 36 is opened high-pressureoutlet liquid flows from line 20 through valve 36, line 34 and orifice60 to the inlet throttle valve. The orifice 60 reduces the pressure ofthe liquid flowing to the inlet throttle valve to slow response movementof the inlet throttle valve spool toward the closed position.Restriction 60 prevents bottoming of the inlet throttle valve spool onthe body of the valve with possible injury to the spool and valve.Preferably restriction 60 reduces the pressure of fluid flowing fromline 20 to the inlet throttle valve so that during rapid shutdown of theengine from high speed operation with high output pressure in line 20the inlet throttle valve is moved in a closing direction to a positionflowing a minimum volume of oil to pump 22 sufficient for low RPM oridle operation of the engine.

[0045] Restriction 60 is provided in the flow path from high-pressureoutput line 20 to the inlet throttle valve 24. The restriction need notbe located in line 34 as illustrated. Alternatively, the restriction maybe located in line 40, in valve 36 or in line 42.

[0046]FIG. 5 illustrates control system 110′ which is identical tocontrol system 110 with the exception that a restriction 70 is providedin line 134 between valve 136 and inlet throttle valve 24. Restriction70 reduces the pressure of high-pressure liquid flowed from outlet line20 to the inlet throttle valve in order to prevent overshooting of theinlet throttle valve when valve 136 connects line 138 to line 134, aspreviously described. Restriction 70 may be located in line 134, asillustrated, in line 138 or in valve 136, again as described.

[0047] Control assembly 210′ is identical to assembly 210 with theexception of restriction 80 located in the branch of line 224 leadingdirectly to inlet throttle valve 24. Restriction 80 reduces the pressureof high-pressure liquid flowed from passage 20, through passage 222,valve 220 and passage 224 to the inlet throttle valve, as previouslydescribed. The restriction may be located in passage 222, in valve 220or in the portion of passage 224 adjacent valve 220 as desired.

[0048] The solenoid control valves are preferably acting in order torespond quickly to digital signals received from the ECM. Preferably,the solenoid control valve should be of the poppet type where thesolenoid rapidly moves a low mass poppet into and out of engagement witha seat. Reduction of the mass of the valving member or poppet improvesresponse time of the valve and, consequently, response of the pumpassembly to signals from the ECM.

[0049] While I have illustrated and described a preferred embodiment ofmy invention, it is understood that this capable of modification, and Itherefore do not wish to be limited to the precise details set forth,but desire to avail myself of such changes and alternations as fallwithin the purview of the following claims.

What I claim as my invention:
 1. A pump assembly for flowinghigh-pressure liquid to components of an internal combustion enginehaving an ECM and a sump; the pump assembly including a high-pressurepump; a pump inlet passage; a pump outlet passage; a hydraulic inletthrottle valve for flowing liquid to the pump through the inlet passage,the inlet throttle valve including a spool moveable between open andclosed positions, a spring biasing the spool toward the open position, ahydraulic chamber, the spool including a piston forming a wall of thechamber wherein liquid of the chamber biases the spool toward the closedposition against the spring; and a hydraulic circuit including a firstflow path extending from the outlet passage to the inlet throttle valvechamber; a second flow path extending from the inlet throttle valvechamber to the sump, and a first fast acting two position on/off controlvalve located in said first path, such control valve including a valvingmember having a fully open valve position and a fully closed valveposition, a spring biasing the valving member to one of said positions,a solenoid for moving the valving member to the other of said positionswhen actuated, and a connection between the ECM and the solenoid whereinactuation and deactuation of the solenoid by the ECM rapidly shifts thevalving member between said positions without modulating flow throughthe valve to flow liquid from the outlet passage to the inlet throttlevalve or isolate the inlet throttle valve from the outlet passage. 2.The pump assembly as in claim 1 including a second fast acting twoposition on/off control valve located in said second path.